This invention relates to a bundling fastener for bars and wires, which bundles bars and wires such as electric cables and pipes and fastens them as bundled to a support.
In places congested with electric wires such as electric appliances having internal wiring and vehicles having wires connecting various electric devices, it is a common practice for those electric wires laid in one general direction to be bundled at proper points selected in the common direction of their length and for the bundled points of the wires to be fastened to a support such as a chassis so as to keep the wires from swaying unsteadily.
A bundling fastener to be used for these and other similar applications, by nature, is composed of a bundling member serving to bundle a plurality of electric wires and a fastener member serving to fasten the wires as bundled to a support such as a chassis. Generally, the fastener member makes use of the construction of a well-known plastic fastener or rivet. To be specific, the fastener member comprises a head portion and a resilient engaging element extended downwardly from the head portion and adapted to snap into engagement with the edge of a fitting hole bored in advance in the support.
In the conventional bundling fastener of this type, the fastener member has a construction basically similar to the construction described above and poses no particular problem. The bundling member, however, has been proposed in various designs. All these designs have had inherent drawbacks.
In one typical conventional device, the head portion of the fastener member is molded in the shape of a circularly or rectangularly curved frame containing an opening at one point thereof, and the curved frame so formed is utilized as a bundling member which serves to receive given bars or wires through the opening in the frame and hold them fast in position therein (as disclosed in U.S. Pat. No. 3,905,570 and No. 4,023,758, for example).
In this bundling member, however, since the size of the frame or the vacant space enclosed in the frame for admitting bars or wires is fixed at the time of the molding, the total diameter of bars or wires to be received (the diameter of the bundle of electric wires or the number of electric wires in the bundle) is fixed from the beginning. The bundling member, therefore, is incapable of bundling bars or wires whose total bundle diameter exceeds the frame's vacant space. In the case of bars or wires whose total bundle diameter is smaller than the frame's vacant space, they find ample room for play. In either case, the bundling member falls short of fulfilling its function.
In other devices, bundling members are in the form of so-called bundling straps (as disclosed in Japanese Unexamined Patent Publications No. 1094/1978 and No. 135722/1979, for example). They assume the general shape of strips. Each of these strips is provided at one end thereof with a bundle and at the other end thereof with a multiplicity of engaging claws, engaging holes, etc. adapted to be slid in the buckle and brought into fast engagement with the buckle. After the strip has been looped round given bars or wires, the loose end containing the aforementioned engaging means is inserted into the buckle. The loose end drawn out of the exit side of the buckle is given a pull to tighten the loop round the bars or wires bundled therewith.
Although this bundling member is highly advantageous in the sense of giving a generous allowance for bundle diameter, the loose end of the strap which stick out of the buckle after the tightening of the bundle is often a nuisance. The bundling member, therefore, has the disadvantage of inferior space factor. To avoid this trouble, there is entailed the extra work of cutting off the useless loose end of the strap. Besides, the work of inserting the loose end of the strap into the buckle within a limited space and then pulling it out of the buckle with considerable amount of force proves to be very troublesome.
In still other devices, a given bundle of electric wires, for example, is simply set in position on the head portion of a fastener member and then is fastened in that position by being forcibly covered with a cylinder (as disclosed in U.S. Pat. No. 3,944,177 and No. 4,061,299, for example). These devices lack allowance for bundle diameter and entail complex work.